Question 1192432
<pre>
Finish the chart by putting in the totals in a new
column on the right, and also in a new row on the
bottom.  When you add correctly across and down, 
you should get the same number in the bottom
right for both totals. In this case 320.
 
       ---------------------------------- 
       | Light smoker | Smoker | Totals |
-----------------------------------------
Men    |      50      |  200   |  250   |  
-----------------------------------------
Women  |      60      |   10   |   70   |
-----------------------------------------
Totals |     110      |  210   |  320   |
-----------------------------------------
</pre>Find the probability that a person selected is a man 
or a light smoker,<pre>
I'll color red all the ones that are either a man or a light smoker:

       ---------------------------------- 
       | Light smoker | Smoker | Totals |
-----------------------------------------
Men    |      <font color="red"><b>50</font></b>      |  <font color="red"><b>200</font></b>   |  250   |  
-----------------------------------------
Women  |      <font color="red"><b>60</font></b>      |   10   |   70   |
-----------------------------------------
Totals |     110      |  210   |  320   |
-----------------------------------------

That's 50+200+60 = 310 out of 320, or 310/320,
which reduces to 31/32.</pre>
Find the probability that a person selected is woman or light smoker,<pre>

       ---------------------------------- 
       | Light smoker | Smoker | Totals |
-----------------------------------------
Men    |      <font color="red"><b>50</font></b>      |  200   |  250   |  
-----------------------------------------
Women  |      <font color="red"><b>10</font></b>      |   <font color="red"><b>60</font></b>   |   70   |
-----------------------------------------
Totals |     110      |  210   |  320   |
-----------------------------------------

That's 50+10+60 = 120 out of 320, or 120/320,
which reduces to 3/8.</pre>
Find the probability that a person selected is a smoker man,<pre>

       ---------------------------------- 
       | Light smoker | Smoker | Totals |
-----------------------------------------
Men    |      50      |  <font color="red"><b>200</font></b>   |  250   |  
-----------------------------------------
Women  |      60      |   10   |   70   |
-----------------------------------------
Totals |     110      |  210   |  320   |
-----------------------------------------

That's 200 out of 320, or 200/320,
which reduces to 5/8.</pre>
If a man is selected Find the probability that he is a smoker?<pre>
This one is different because we are given that a man is selected.
We were not given that in the others. So we eliminate the women
and the total, for the total includes the women.

       ---------------------------------- 
       | Light smoker | Smoker | Totals |
-----------------------------------------
Men    |      50      |  <font color="red"><b>200</font></b>   |  250   |  
-----------------------------------------
<s>Women  |      60      |   10   |   70   |
-----------------------------------------
Totals |     110      |  210   |  320   |</s>
-----------------------------------------

So this is just the 200 out of the 250, or 200/250,
which reduces to 4/5.

Edwin</pre>